Rigid–flexible coupling dynamics of a threaded reusable low-shock spacecraft separation device

Threaded separation devices are widely used in space launches due to their advantages of reusability and low shock. Analyzing the dynamics of the separation process is crucial for enhancing separation reliability and accuracy. However, the inevitable presence of nonsmooth factors, such as complex geometric surface contact and instantaneous impact between components of the device, brings significant challenges for efficiently simulating the dynamics of the separation process, particularly when using the widely adopted finite element method. Therefore, this paper aims to build up an efficient rigid–flexible coupling dynamics model for a thread separation device. Firstly, a highly efficient thread contact dynamics model is proposed, in which the bolts in the device are modeled as elastic bars with tension-torsion coupling deformation, and the thread is represented as a cantilever beam fixed on the bar. This efficient model enables the analytical determination of the threaded contact force based on the compatibility conditions and constitutive relations for thread deformation. Next, contact forces including guide constrains and band pretension on the bolt are calculated through compliance model. Then, an efficient multibody dynamics equation for the device is established, and its dimension is reduced through the assumed model method. Finally, the proposed model is used to study the static tension and torsion distributions in the bolt before separation, as well as the dynamic responses during a separation process. The validity of the proposed model is confirmed through three-dimensional finite element analysis. In addition, influences of geometrical and material parameters on separation response were investigated. Based on the proposed model, influences of geometrical and material parameters on separation response were investigated. The proposed model will provide a method to perform extensive simulations for facilitating the design and optimization of separation devices. Furthermore, it provides new insights into efficient simulation analysis for general threaded drive systems.